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A119993
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a(n) = n-th prime from among those primes which are coprime to n.
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4
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2, 5, 7, 11, 13, 19, 19, 23, 29, 37, 37, 43, 43, 53, 59, 59, 61, 71, 71, 79, 83, 89, 89, 101, 101, 107, 107, 113, 113, 137, 131, 137, 149, 151, 157, 163, 163, 173, 179, 181, 181, 197, 193, 199, 211, 223, 223, 229, 229, 239, 241, 251, 251, 263, 269, 271, 277, 281
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OFFSET
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1,1
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LINKS
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FORMULA
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EXAMPLE
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5,7,11,13,17,19,23,... is the sequence of primes which are coprime to 6. 19 is the 6th such prime, so a(6) = 19.
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MAPLE
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f:= n -> ithprime(n + nops(numtheory:-factorset(n)));
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MATHEMATICA
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With[{prs=Prime[Range[1000]]}, Table[Select[prs, CoprimeQ[#, n]&][[n]], {n, 60}]] (* Harvey P. Dale, Aug 27 2014 *)
Table[Prime[n + PrimeNu[n]], {n, 60}] (* Jon Maiga, Jan 05 2019 *)
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PROG
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(PARI) {m=59; for(n=1, m, q=2; k=n; while(k>0, p=q; if(gcd(p, n)==1, k--); q=nextprime(p+1)); print1(p, ", "))} \\ Klaus Brockhaus, Aug 15 2006
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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